Generally, four stroke internal combustion engines utilized valves to allow exhaust to leave the working (combustion) chamber of the engine cylinder after the combustion stroke, as well as to allow a new air charge to enter the cylinder to begin the cycle anew during the intake stroke. Two stroke internal combustion engines on the other hand may utilize valves for both intake and exhaust or a valve for intake and a port for exhaust. Such valves have traditionally been invariably actuated by a cam affixed to a shaft (the cam shaft), or alternatively by an electromagnetic or hydraulic device.
It would be greatly advantageous to provide another more efficient way to actuate valve reciprocation on internal combustion engines. Valves which rely on a cam shaft usually require heavy springs and a large number of other moving parts that absorb a large amount of energy and create a great deal of friction. Additionally, such systems are relatively expensive to operate.
U.S. Pat. No. 6,349,691 to Klein (one of the inventors named herein) describes a partial solution in the form of a valve for air intake. The valve is responsive to pressure differential between the manifold and combustion chamber. Specifically, the valve closes in response to the increase in pressure in the cylinder as the piston rises (after passing bottom dead center and approaching the top of the cylinder). Unfortunately, a problem with this intake valve assembly is that inertia and, to a lesser extent friction, retards the valve's speedy closure, thus negatively affecting engine performance.
Therefore, it would be advantageous to provide an externally regulated pressure actuated valve system.
The present inventors have also filed U.S. patent application Ser. No. 10/449,754 on May 30, 2003, which introduces a system of using a spring to accelerate the valve closing, and a means to vary non-cyclically the base force of the spring so that the proper amount of spring force can be used under varying conditions of engine speed and load. While this variable spring force intake valve system is reliable, it still presents a lingering concern. Specifically, when the spring force is adjusted (i.e. during a regime of higher engine speed) the period of time during which the valve is open to allow ventilation is shortened. Thus, an insufficient amount of intake air enters the cylinders, negatively effecting engine performance.
Additionally, the present inventors have filed a U.S. Provisional Patent Application No. 60/444,532 on Jan. 31, 2003, which introduced another more energy efficient intake valve assembly. The provisional patent application disclosed both a unique compressed air actuated intake valve system (either wholly air operated or spring-assisted) and a unique air distribution system using a single air source for actuating the intake valve. The valve is short and lightweight, having collar. The valve sits in a housing atop an engine cylinder and is connected to the air distribution system. Compressed air is either directed over the top of the valve forcing it downward and open or into a hollow chamber within the valve housing where the compressed-air applies pressure under the valve collar, forcing the valve upward and closed. The disclosed air distribution system uses a rotating disk assembly with air outlets to direct airflow as necessary to raise and lower the valve. While the valve assembly disclosed in this provisional patent application is sound, there is a slight disadvantage associated with this air distribution system. Namely, the air distribution system, as disclosed, requires lubrication for the rotating disks and upon heating the presently available lubrications may release unwanted and harmful hydrocarbons into the atmosphere. Additionally, the valve was illustrated for use only as an intake valve, not as either an intake or exhaust valve.
It would be advantageous over the prior art to provide a wholly forced-air actuated valve system, using one or multiple air sources, operable on either a four stroke or a two stroke internal combustion engine, to open and/or close intake and/or exhaust valves. It would also be advantageous to provide a system for efficiently regulating the timing of the valve open/close (reciprocation) cycle relative to the engine speed. It would further be advantageous to provide such a system that does not require the use of lubricants that may release harmful by-products into the environment.